You should've included GBA. Because looking at this you can see Nintendos thought process. From GB to GBC they clearly just made it a color GB. Then they elongated it for GBA. And they added a hinge to the GBC for the SP. And then they were like, "Wtf why didn't we do both of those things?" and the DS was born. And then they were like, "Hold on, this doesn't look big enough and with these 3d games this D-pad won't do."